Dental impression accessory



Oct. 5, 1948. R. E. \HAWKINSON DENTAL IMPRESS ION ACCES SORY Filed May 29, 1946 E. 1L4: INVENTORT 5' 774g flan 1:91.501:- v

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Patented Oct. 5, 1948 UNITED STATES PATENT OFFICE DENTAL IMPRESSION ACCESSORY Roy E. Hawkinson, Bloomfield Hills, Mich. Application May 29, 1946, Serial No. 672,971

7 Claims. 1

This invention relates to dental apparatus and more particularly to improved dental matrices and forceps for use therewith.

Dentists, in making inlays for a tooth, make an impression of the cavity with wax and, in doing this, the wax is usually app-lied to a metal backing member, usually termed a matrix, which is used not only as a support for the wax, but as a backing member for the wax so that it may be forced firmly into the cavity and the metal backing member brought .toward a flush relationship with the surface of the tooth to fully determine the size, shape, and cont-our of the cavity.

These metal backing members present a prob" lem as far as manipulation is concerned. While devices of this general type have been previously sold to the dental trade, none of these seems to be entirely satisfactory. While some of these devices do provide a means whereby the plate can be directed in its application when pressure is ap" plied through the dental tool to the matrix, the dentists hand or arm often trembles in applying this pressure and this trembling is transmitted to the matrix and to the wax, with the result that an imperfect impression is obtained. Other devices previously employed provide a fairly satisfactory means for applying pressure, but lack.

means for controlling the in respect to the tooth.

It is, therefore, an object of this invention to provide a matrix having an upstanding lu thereon which, when grasped by dental forceps, gives absolute control and placement of the matrix in relation to the tooth. Once the matrix is placed. the forceps may be removed from the sides of the lug and applied to the top of said lug in such a manner that even though the hand of the dentist positioning of the plate trembles there will be no relative movement between the matrix and the tooth.

It is a further object of this invention to provide a matrix capable of being out and fitted to the con-tour of any tooth, or any portion thereof of said tooth.

It is a further object of this invention to provide a matrix so constructed as to displace overlapping gum tissue around the cavity so that all margins of said cavity are accessible to the wax or compound.

It is a still further object of this invention to provide a dental matrix having an upstanding rib rigidly secured to the center thereof and grooves along each side of said rib adapted to be engaged by dental forceps so as to firmly hold and control the positioning of the matrix with respect to any cavity or tooth.

It is a still further object of this invention to provide a matrix having an upstanding rib rigidly secured to the center thereof and said rib having a head formed at the top thereof, said head h-av ing a depression therein adapted to receive the end of dental forceps so that if the dentists hand trembles when applying pressure to saidmatrix there will be no relative movement between the Plate and the tooth.

It is a still further object of this invention to provide a dental matrix having an upstanding rib mounted at an angle of less than with relation to the plane of said matrix to keep the head of said rib from contacting and injuring the gum, especially where the cavity is below the gum line and'so that when pressure is applied to said rib it will tend to tip said matrix in and hold it more closely to said tooth.

It is a still further object to provide a dental matrix comprising a cross-shaped plate, the arms of which are adapted to be bent downwardly to surroundingly encompass a tooth, which takes the place of the usual band type matrix and is capable of fitting any size tooth, while the convention-a1 band must be provided in a plurality of sizes to fit different sized teeth, especially in cases where the cavity is in the top of the tooth or in any case where the matrix can be withdrawn upwardly with an impression. This matrix is further provided with an upstanding rib adapted to be grasped by dental forceps.

It is a still further object to provide forceps having relatively pivotal jaws and a forwardly facing shoulder on the inner surface of one of said jaws adjacent the outer end thereof adapted for use as dental apparatus and, in a more limited aspect, for use with dental matrices of the type designated.

These and other objects of my invention will be ance with the present invention, the matrix being shown of a stock size as furnished to the den tal trade;

Figure 2 is a perspective view of the embodiment shown in Figure 1 in which the matrix has been cut to size to fit a particular tooth;

Figure 3 is an end view of the matrix and rib shown in Figure 2; r

Figure 4 is a perspective view of the matrix and rib and dental forceps grasping rib;

the sides of said. 7

-- merely bending plate Figure 5 is a side view of the embodiment shown in Figure 4;

Figure 6 is a side View of the embodiment shown in Figure 5, showing the forceps applied to a groove in the top of the rib;

Figure 7 is a side view of the embodiment shown in Figure 5, showing the point of the dental forceps inserted in a depression in the top of said rib;

Figure 8 is: a sectional view taken along the line 8-8 of Figure 5;

Figure 9 is a front elevation of a tooth with a cavity below the gum line;

Figure 10 is a sectional view taken along the line I 0 of Figure 9;

Figure 11 is a view similar to that of Figure 10, but showing the matrix and wax initially positioned in relation to the cavity;

Figure 12 is a view similar to Figure 11' showing the matrix in position after pressure has been applied to it;

Figure 13 is a perspective view of a modification of the matrix previously shown, and

Figure 14 is a side view in section of a tooth illustrating. a use of the embodiment shown in Figure 13.

A, matrix l5, as shown. inFigure 1, comprises a platev l6 made of a thin ductile material capable of being easily cut in a dentists office as by scissors or shears to fit or cavity therein. An upstanding rib I! is rigidly secured to the center of matrix plate E6. The upper end of. rib I1 is formed into a head 59 having longitudinally overhanging flanges 2| in relation to rib H. The lower surface of flanges 2i. and the upper surface of plate I6 form longitudinal grooves 23. along each. side of the rib ll. These grooves 23 are adapted to receive the ends of dental forceps 25 so as to provide holding means for said matrix I5, when positioning it in relation to a tooth 21,. and prevent the forceps from pulling off the rib when removing the plate and impression from the cavity. Groove 29 extends longitudinally and centrally along the top of rib head l9, and in the center of groove 29 a hole or depression 3| is preferably provided, adapted to receive the pointed end of forceps 25. Rib IT is preferably arranged at an angle of less than 90 in. relation to the longitudinal axis of matrix I5, as shown. This angular mounting of rib l1 permits easier placement of the matrix because it keeps the rib away from the gum so that the dentist can place the matrix without contacting or injuring the gum with. either the dental forceps or the rib head, especially where the. cavity is below the gum line and it also tends to tip matrix I inwardly and hold it clos to tooth 21. Forceps 25 can be of any conventional pivoted or spring jaw type and have the ends thereof adapted to fit into the grooves 23 and 29 provided'on rib and rib head 19, respectively.

In operation, if, for example, a. tooth 21 has a cavity 35 below the line of gum 31, this flat, type matrix I 5 can easily be adapted for use therewith. The dentist, by merely taking a pair of shears, can cut plate Hi to the size desired so as to displace gum 3! the correct amount necessary toget at cavity 35 without any surgical operation. By I 6 with the fingers it can be formed to the contour necessary to fit the tooth around the margin of the cavity. Heated. wax can then be placed against the inward surface of the plate I6 and by grasping the sides of rib I21; below the head portion, with the forceps, the matrix and wax can be positioned properl with the contour of any tooth sions of cavities without any relation to the cavity. After this positioning, the forceps 25 can be removed from the side of the rib and the forceps end can be placed either in the groove 29 at the top of the rib, as shown in Fig. 6, or the pointed end of the forceps can be placed in the depression 3| at the top of rib H, as shown in Fig. 7. Due to the rib construction and manner it is mounted, pressure can be applied against the rib and plate forcing the wax into the cavity so as to obtain a perfect impression of the cavity without the dentist worrying about any trembling of his hand which might cause an imperfection in the impression. After the wax is forced into the cavity, the forceps can be removed from the top of rib H and again placed around the side of the rib in grooves 23 and the matrix and wax can be removed without damaging the impression of the wax which has been formed. During such removal, engagement of the ends of the forceps 25 with the undersides of the head l9 serves to prevent the forceps from slipping off the rib II.

In accordance with a more limited phase of the invention,.the forceps 25 are preferably provided with a shoulder 41 on the inside surface of at least one of the jaws. When the forceps are positioned in grooves 23 along the sides of the rib, this shoulder abuts against the rear portion of rib l1 and prevents any slippage, whichv might occur if no shoulder were provided, when pressure is applied longitudinally of the forceps.

A modification of the embodiment shown in Figures 1 and 2 is illustrated in Figure 13 where the matrix comprises a cross-shaped plate 43 having four projecting arms 45. The four arms 45 can easily be bent over forming an enclosing cap for the tooth 41. The ends of the arms may be cut oh so as not to dig into the gums when the plate 43 is pressed downwardly to form a Wax impression of the cavity in the top of the tooth 41. Again the upstanding rib H is mounted in the center of the matrix l5 and the construction of this rib is identical with that previously described. This matrix 45 is adapted to be used where the cavity in the tooth 47 is in the top of the tooth or in any case Where the matrix can be Withdrawn upwardly with an impression.

In operation, the forceps are used in identically the same manner'with this modification as with that previously described. Once again the arrangement of therib, with the groove provided therein, prevents any relative movement between the matrix and the tooth if the dentists hand or arm should tremble while applying pressure through the forceps.

It will likewise be seen that this cross shaped matrix 43 can readily be made into a matrix of the type shown inFigures l and 2, or any other desired shape, by merely cutting oif any of the arms 45 not needed. This would mean only one production item, namely the cross shaped matrix, need be made for making impressions of cavities, in the top of a tooth as shown in Figure 14, and for making impressions of cavities in the side of a-tooth, or elsewhere, as illustrated in Figure 9. The loss of metal due. to cuttin off the arms, when desired, would be insignificant, and the time required to perform this operation, likewise would be little.

It will thus be seen that I. have provided a matrix and forceps for use therewith which when used in combination or when the matrix is used singly with any suitable pair of forceps will provide an efiective method of making wax. impresworry on the part of the dentist of poor impressions being made due to trembling or movement of his arm, or due to trouble in manipulation for teeth in the mouth of which it is ordinarily difficult to make impressions.

While I have described several embodiments of my invention, it is to be understood that I do not wish to be restricted thereto and that I intend to cover all modifications thereof which would be apparent to one skilled in the art and would come within the spirit and scope of the appended claims.

I claim:

1. A dental matrix comprising a relatively thin plate adapted to be formed to the contour of a tooth or any portion thereof, an upstanding rib rigidly secured thereto, a transversely extending head portion at the upper end of said rib, said rib mounted at an angle of less than 90 to the plane of said plate whereby to prevent said head from contacting the gum portion surrounding said tooth.

2. A dental matrix comprising a relatively thin plate adapted to be formed to the contour of a tooth or any portion thereof, an upstanding rib rigidly secured thereto, a transversely extending head portion at the upper end thereof, said head portion and said plate forming a groove on each side of said rib adapted to receive the end of dental forceps whereby to permit accurate positioning of said matrix.

3. A dental matrix comprising a relatively thin dental plate adapted to be formed to the contour of a tooth or any portion thereof, an upstandin rib rigidly secured thereto, a transversely extending head portion at the upper end thereof, said head portion forming the walls of a depression therein adapted to receive and aid in retaining the end of dental forceps.

4. A dental matrix comprising a relatively thin plate of ductile metal adapted to be formed to the contour of a tooth or any portion thereof, an upstanding rib rigidly secured thereto, a transversely extending head portion at the upper edge of said rib, said head portion forming the walls of a depression therein adapted to receive the end of dental forceps, said head portion and said plate forming a groove on each side of said rib adapted to receive the end of dental forceps.

5. A dental matrix comprising a thin ductile metal plate adapted to be formed to the contour of a tooth or any portion thereof, an upstanding rib rigidly secured to the center thereof, a transversely extending head portion at the upper edge of said rib, said head portion having a longitudinal groove therein adapted to receive one end of dental forceps, said h'ead provided with a depression in its center adapted to receive the point of dental forceps, said head portion and said plate forming a groove on each side of said rib adapted to receive the end of dental forceps to permit accurate positioning of said matrix.

6. A dental matrix comprising ductile, cross-shaped plate adapted to be applied to the exposed end of a tooth and have its arm bent to surroundingly encompass a tooth, said matrix adapted to be out to fit any size tooth, an upstanding rib rigidly secured thereto for accurate positioning of said matrix and for applying pressure to said matrix to obtain an impression of a tooth or any portion thereof.

7. A dental matrix comprising a relatively thin, cross-shaped plate adapted to be applied to the exposed end of a tooth and have its arm-s bent to surroundingly encompass adapted to be cut to fit any size tooth, an upstanding rib rigidly secured thereto, a transversely extending head portion at the upper end thereof, said head portion forming the walls of a longitudinally extending groove therein adapted to receive the end of dental forceps, said head provided with a depression in the center thereof adapted to receive the pointed end of dental forceps, said head portion and said plate forming a groove on each side of said rib adapted to receive the end of dental forceps to position accurately said matrix,

ROY E. HAWKINSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,257,947 Sternberg Feb. 26, 1918 1,349,767 Ivory Aug. 1'7, 1920 2,099,454 Siqueland... Nov. 16, 1937 a relatively thin,

the tooth, said matrix 

